what went wrong?

I put 18 silverlace wing eggs, 6 light sussex, and 6 duck eggs in my incubator. The chickens were due to hatch 3rd aug by the 8th only 6 hatched so i opened the rest to see and they were all fully formed but dead and they still had the yoke sak out side of there body. What did i do wrong? I kept the 2 water troughs toped up with tepid water, on open it once a day. Only 1 out of the 6 ducks hatched an again the same thing all fully formed but dead? So disapointing. I was going to get some Ixworths next but after this desaster im very reluctant. Please advise. Many thanks

I wonder if you had some sort of temperature incident with your incubator. It sounds like your eggs all died at the same point, which points to something going wrong in your incubator. I'm so sorry for your poor hatch.

Also, if the eggs were shipped, that can impact your hatch rates as well.